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(1→3),(1→6)-β-D-Glucan, a cell wall polysaccharide in many microorganisms, fungi and algae, is a well-known biological response modifier. Recently, it was found that (1→3)-β-D-glucan from Saccharomyces cerevisiae also exhibits antioxidative capabilities. In this study the antioxidative activity of the cell wall fractions of brewer's yeast was investigated. Particular emphasis was put on the question to which extent glucan is responsible for the antioxidative activity of the cell walls and how the other cell wall components might contribute. For the experiments yeast cell walls from brewery fermentations were used. Glucan was isolated by a three-step extraction procedure including a combination of hot water and enzymatic treatment. The level of (1→3),(1→6)-β-D-glucan in the cell walls was analyzed enzymatically. The antioxidant activity was determined by electron paramagnetic resonance spectrometry and Trolox equivalent antioxidant capacity assay. The results show that the antioxidative activity of yeast cell wall proteins exceeds that of β-glucan greatly. Especially aromatic side chains and free thiols from denatured proteins seem to work as antioxidants.

Triggering Dectin-1-Pathway Alone Is Not Sufficient to Induce Cytokine Production by Murine Macrophages.

β-glucans (BG) are abundant polysaccharides of the Saccharomyces cerevisiae cell wall (Sc CW), an industry byproduct. They have immuno-stimulatory properties upon engagement of dectin-1 (Clec7a), their main receptor on particular immune cells, and they actually become of great interest because of their preventive or therapeutic potentials. Zymosan, a crude extract of Sc CW was studied as a prototypic BG, despite its miscellaneous PAMPs content. Here, we examined the response of murine wild type or Clec7a-/- bone marrow-derived macrophages (BMDM) to products with increasing BG content (15, 65 or 75%) and compared their effects with those of other dectin-1 ligands. The enrichment process removed TLR ligands while preserving dectin-1 activity. The most enriched extracts have very low NFκB activity and triggered low amounts of cytokine production in contrast with crude products like zymosan and BG15. Furthermore, MyD88-/- BMDM did not produce TNFα in response to crude Sc CW extracts, whereas their response to BG-enriched extracts was unaffected, suggesting that BG alone are not able to initiate cytokine secretion. Although Sc CW-derived BG stimulated the late and strong expression of Csf2 in a dectin-1-dependent manner, they remain poor inducers of chemokine and cytokine production in murine macrophages.

Quantification of 1,3-β-D-glucan from yeast added as a functional ingredient to bread.

Due to their immunomodulatory effect, 1,3-β-G from yeast are used as functional ingredients, but reliable methods for their detection in foods are lacking. We have adapted a method based on fluorescence detection with aniline blue to quantify the amount of five commercial yeast β-glucan preparations added to crisp or yeast-leavened bread. This assay detected yeast β-glucan preparations added to different breads with an average recovery of 90, 96, 99 and 105%, while one of the preparations was overestimated, with an average recovery of 157%. The presence of cereal 1,3-1,4-β-D-glucans did not interfere with assay performance. The addition of 1,3-β-G at 0.2 and 0.5 g/100 g is low compared to the recommended dose of 1,3-β-G per serving demonstrating assay sensitivity. However, more research is needed to fully understand 1,3-β-G conformation/structure on aniline blue interaction as well as the effect of baking on structure and dissolution properties of yeast β-glucans.

Isolation of Functional Components β-Glucan and γ-Amino Butyric Acid from Raw and Germinated Barnyard Millet (Echinochloa frumentaceae) and their Characterization.

The study was carried out to analyze the characteristics of two functional constituents’ viz. γ-amino butyric acid (GABA) and β-glucan extracted from raw and germination barnyard millet (var. PRJ-1). A significant (P ≤ 0.05) effect of germination (sprouting) was observed in yield, chemical composition, functional, rheological and antioxidant properties of β-glucan and GABA. The yield of GABA extract was 12.34 % and the content increased from 6.37 mg/100 g in raw to 35.70 mg/100 g in germinated sample. The DPPH, total antioxidant and hydrogen peroxide scavenging activities of GABA extract increased after germination from 45.34 to 65.34 %, 15.3 to 33.3 millimole/g and 38.4 to 64.7 millimole/g, respectively. The yield of β-glucan extract of raw and germinated flour was 6.05 and 5.01 % whereas the β-glucan contents were 83.30 and 79.64 %, respectively. The functional properties of β-glucan i.e. , swelling power, water binding capacity and DPPH scavenging activity increased from 1.45 to 1.76 g/g, 2.13 to 2.32 g/g and 44.39 to 57.42 %, respectively, after germination. Similarly there was an increase in the storage modulus after germination process which attributes a better viscoelastic capacity of β-glucan at low frequencies. The results exploit that the β-glucan and GABA might promise a polymeric incipient to be implemented as food additives with variable functional and structural characteristics.